text: Electrofusion welding requires electrical current to be passed through the coils implanted in the fittings. Since the electrical energy input is an excellent indicator of the joint strength that develops during fusion, it is necessary to have consistent electrical power input. Energy input during the joining process is typically measured by controlling the time it takes for the current to pass through the fitting. However, energy input can also be monitored by controlling overall temperature, molten polymer temperature, or molten polymer pressure. 
  A control box takes electrical power from a generator and converts it into an appropriate voltage and current for electrofusion joining. This provides consistent energy input for each application. The most common input voltage for electrofusion welding fittings is 39.5V, as it provides the best results without risking operator safety. The current is input as an alternating current (AC) waveform.